The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Light Emitting Diodes (LEDs) have great energy saving effect and can be quasi-permanently used. For this reason, LEDs increasingly find their application in various fields. Specifically, nowadays there is an attempt to replace conventional light sources in streetlamps with LEDs.
However, LEDs have a problem that they generate a larger amount of heat than conventional light sources. When the heat generated by LEDs is not dissipated well, the light efficiency of LEDs is deteriorated and the lifespan of LEDs is shortened.
Therefore, in streetlamps employing LEDs, a heat-dissipating plate having a considerably larger volume and size than an LED board provided with LEDs thereon is attached to the back surface of the LED board so that the heat generated by the LEDs can be released into air and thus be dissipated.
However, the heat radiated from the heat-dissipating plate stays within a casing of a streetlamp. Therefore, even with the use of the heat-dissipating plate, high heat dissipation efficiency cannot be obtained.
In order to solve this problem, a casing of a streetlamp may be provided with a vent hole for ventilation. However, when the casing is provided with a vent hole, since streetlamps are usually installed outdoors, rain water or insects are likely to intrude into the casing, thereby damaging the LED board, which results in deterioration of heat dissipation efficiency of the streetlamp.
Aside from this problem, the casing provided with a vent hole also has the following problem: air around the streetlamp is heated by the heat released from the heat-dissipating plate, and the heated air lingers within the casing and around the streetlamp. For this reason, the casing with a vent hole does not provide satisfactory heat dissipation efficiency.
Meanwhile, in conventional LED streetlamps, output varies from LED to LED, and heat-dissipating plates employed in the LED streetlamps are required to have different sizes according to the LED outputs. Therefore, it is difficult and burdensome to design heat-dissipating plates.
Korean Patent No. 10-0984768 (Sep. 27, 2010) discloses “Streetlamp Capable of Illumination Angle”.
This streetlamp is intended to solve the problems with the conventional LED streetlamps described above. The streetlamp includes a lamp module including LEDs, a casing provided with at least one vent hole and coupled to the lamp module at a lower end thereof, and a cooling fan installed in the casing to purge heat generated by the LED out of the casing.
This conventional technology forms a plurality of vent holes in a casing and operates the cooling fan within the casing, thereby enabling the heat radiated from a heat-dissipating plate to be easily purged from the casing through the vent holes. This technology improves heat dissipation efficiency. In addition, this conventional technology measures an internal temperature of the casing by detecting the heat radiated from the heat-dissipating plate and operates the cooling fan and thus dissipates heat only when the measured temperature is a predetermined temperature or higher. Therefore, even when LEDs having diverse outputs are mounted in an LED streetlamp, it is not necessary to change the structure or design of the heat-dissipating plate.
However, this LED streetlamp has problems described below. Namely, this technology is not feasible in terms of costs because it requires forming a plurality of vent holes in each casing and installing cooling fans within the casings of a number of LED streetlamps and because various sensors and control instruments for selectively operating the cooling fans installed in the LED streetlamps are required. Furthermore, when the cooling fans, sensors, or control instruments malfunction, a heat dissipation effect cannot be obtained. Yet furthermore, it is impractical to individually inspect all of the accessory equipment to check for malfunctioning.
In addition, this technology is based on the premise that external air flows in the casing through the vent holes, then performs heat exchange with the heat-dissipating plate, and finally flows out of the casing through the vent holes. However, when the heat-dissipating plate is provided in a built-in form within the casing, heat exchange is limited due to a narrow space of the casing.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.